Preheater for vaporizers in oil burners



April 8, 1941.

PREHEAI'ER FOR VAPOBIZERS IN OIL BURNERS Filed March 9, 1938 ATTOR/YEYJ J. A. ALMSTROM ETAL' .237.285

Patented Apr. 8, 1941 HE D- PREHEATER FOR VAPORIZE-RS IN om BURNERS J ohn A. Almstriim and Frithiof Ekstrand, Sodertalje, Sweden Application March 9, 1938,.Serial No. 194,970 In Sweden March 10, 1937 1 Claim.

The present invention refers to an improved preheating means for Vaporizers in oil burners, such as petroleum oil stoves, or lamps, and the -1ike, and the object of the invention is to provide a preheater of this kind by means of which the oil burner may be preheated by the same heavy fuel oil ordinarily used in the burner, especially petroleum.

The desired object in preheaters of the type of the present invention has always been to effect a quick and complete combustion of the fuel used so that the preheating operation will consume the least possible time. Heretofore, there have been two usual methods for accomplishing this object, namely by increasing the flow of fuel and by admitting air under pressure in a manner to better support combustion. These heretofore known means, even when used in combination have not been wholly satisfactory.

The present invention is based on the observation of this fact, and it has for its object to provide for an increased admission of fuel oil to the preheating flame in addition to the fuel admission caused by the capillary action of the wick means, and this additional fuel oil admission is performed by means of injection action from the compressed air flow under such conditions that the fuel oil fed into the preheating flame is mechanically subdivided, or atomized, by the air flow simultaneously as it is intimately mixed therewith.

According to the present invention, a wire gauze wick is seated within a container which may be partially'fllled with fuel in any known manner, the fuel to be burned in the preheating operation. This wick co -axially surrounds and extends above an orifice from which air is ejected. The airblast is directed so as not to touch the inner wick edge but to pass close thereto. The injection action spoken of causes the fuel oil in addition to its longitudinal passage through the wick to pass transversely through the wick body, which, being heated by the flame, will cause the fuel thus transversely passing to be vaporized, and this vaporized fuel will be sucked up due to the air blast through the tubular interior of the wick body and blown into the hot flame admixed with the air, this fact increasing the feed of the fuel oil to the flame. Hence, it can be said that the flame consists of two portions, an inner core portion formed by the burning of the vaporized fuel admixed with the air stream, and an outer mantle portion formed by the burning of the more liquid or flowing portion of the oil at the upper edge of the wick.

When the compressed air escapes through the upper tubular end of the gauze wick according to the invention, it causes a reduced air pressure within the space surrounded by the tubular wick and the surrounding atmospheric pressure acting on the oil surface will cause the fuel oil to be pressed into the wick and to pass longitudinally to the upper end thereof as Well as transversely in the direction of the partial vacuum.

An embodiment of the invention suitable for ordinarypetrolem oil stoves is illustrated in the accompanying drawing and. seen in elevation, partly in section.

In the ordinary manner, the oil stove is provided with a fuel container 1 having a filling stud 2, and besides the said container is provided with suitable means (not shown) for creating an air pressure therein above the level of the fuel oil supply. The container is also provided with a pipe 3 for the fuel oil, such pipe extending downwardly adjacent tothe bottom of the container, and the upper end of the same is screwed on to a vaporizing burner l provided with a nozzle 5, in the conventional manner. A cup 6 is positioned at a level a little below the orifice of the fuel nozzle and adapted to take up a' suitable quantity of preheating fuel oil, and a wick means 1 having capillary action is mounted in the cup 6 at a little distance around the nozzle centrally positioned therein, such wick means being substantially cylindrical and having a pair of recesses at its upper end for facilitating the cleaning of the nozzle 5.

As will be seen from the drawing, the wick 7 extends upwardly to a level substantially be-' yond the outlet orifice of the nozzle 5, and downwardly to the bottom of the cup 6 so as to be adapted'to convey fuel oil therefrom as long as the supply permits it. v

The pipe 3 is provided with a branch pipe [2 communicating with the interior of the pipe 3 at a level above the fuel container needle valve I0 is provided in the branch pipe 9 and surrounded by a stufling box i l penetrated by the free end of the valve spindle which is provided with a knob for manual operation. The pipe 9 stands also in connection with the upper and air filled space of the fuel container l by means of a channel l3.

The operation of the device is as follows:

When a suitable quantity of preheating fuel oil has been introduced into the cup 6, such fuel is ignited, and naturally it will be sucked up by l, and a will cause the oil to be pressed into the wick and to pass longitudinally to the upper'end thereof as well as transversely therethrough.

This injection action is auxiliary to the capillarity of the wick. The fuel entering the flame from the upper edge of the wick is still in a.

liquid state but due to the induced air flow, it has been mechanically subdivided and will be immediately burned upon entrance to the flame.

In order to facilitate the mechanical subdivision of the fuel oil, the wick means ought to be made from wire netting of fine .mesh (for instance nickel or phosphor-bronze) and preferably in one or more concentric layers, which involves the advantage that the wick is not burnt itself.

By actuation of the air compressor (pump) of the oil stove and by suitable control of the valve means H, the air admitted to the preheating flame may be controlled both in respect of quantity per unit of time and in respect of pressure, so that the preheating flame may be controlled under all conditions. It is possible to control the rate of burning by adjustment of the amount of air supplied by the nozzle 5.

As soon as the burner 4 becomes heated to some degree, the compressed air will also be heated in a corresponding degree, and this circumstance will successively improve the combustion. When the burner 4 itself has been sufficiently heated for vaporization of the fuel, the needle valve I0 is closed, and when still more air is pumped into the fuel oil container I, the fuel therein will be raised through the pipe 3 and the burner to the nozzle 5, whereupon the burner is in action in the ordinary manner.

By suitable dimensioning of the cup 6, or by other means, the quantity of preheating fuel oil introduced into said cup shall naturally be measured so that one single fuel charge therein will be suflicient for preheating of the burner 4 to a suflicient degree, and that the whole quantity of preheating fuel oil has been consumed substantially simultaneously with the obtaining of said sufficient degree of preheating.

It will naturally be possible to modify the embodiment of the invention described above Within the scope of invention and While maintaining the functioning thereof.

The construction of the means used for admission of the compressed air to the preheating flame is of secondary importance to the inven-- tion, and it is only important that the air flow acts on the fuel conveyed by the wick means in the manner described. The construction of the wick means itself is also rather irrelevant while adhering to the condition that it is placed in such a relation to the orifice of the air nozzle that the air flow discharged therefrom results in the injection action upon and the mechanical subdivision of the fuel as described. It is naturally not sufficient by means of the injection action to increase the delivery of the fuel oil to the upper end of the wick means only, and it is similarly important that the quantity of fuel thus additionaly delivered to said edge shall also be effectively fed into the flame. From this reason the injection action described is fully coordinated with the forced mechanical conveyance of the fuel, which simultaneously results in the desired subdivision thereof, for obtaining the desired result.

The cup 6 may also be dispensed with if other means are provided for conveying a suitablequantity of preheating fuel oil to the lower end of the wick means, and the shape of the wick means as well as the material used therein may also be varied in correspondence with and in order to suit the shape, or type, of burners used in each specific instance.

What we claim and desire to secure by Letters Patent is:

A preheating burner comprising, a cu -shaped receptacle, an air duct passing axially through said receptacle and discharging axially through a constricted orifice, a substantially cylindrical heat conducting metallic gauze wick positioned upon the bottom of the receptacle and radially spaced from said air duct and the walls of said receptacle, said wick extending above the discharge orifice of said duct, and means to supply air under pressure to said duct whereby when the receptacle is partially filled with petroleum and ignited and air under pressure is caused to pass through the orifice, the pressure in the zone defined between the wick and duct will be lower than the pressure in the zone defined between the receptacle and the wick, and the combined action of capillarity, air discharge and conduction of heat to the petroleum through the medium of the wick will cause petroleum in the upper portion of the wick to vaporize or approach vaporization while a flow of air will be induced to cause said partially vaporized petroleum to pass radially through the wick in a direction toward said air duct and to be entrained for burning thereabove. H

JOHN A. ALMSTROM.

FRITIHOF EKSTRAND. 

